Hydraulic hand tool

ABSTRACT

The specification discloses a hydraulic pressure operated hand tool of the type in which manual pressure exerted on a small-area pump piston creates a hydraulic pressure which is communicated to a power cylinder for activating a hand tool jaw member, such as a cutter blade. Preliminary take-up movement of the cutter blade into contact with the object to be severed, such as cables, pipe etc., is effected by manual pressure applied to a second pump piston of relatively large area, which causes rapid displacement of the hydraulic medium from a reservoir to the power cylinder before exertion of manual pressure to the small-area pump piston. A push-button valve when pressed causes instant return displacement of hydraulic medium via a by-pass communication from the cylinder to the reservoir to relieve the activating pressure on the cutter blade and restore it promptly to normal position.

United States Patent 1191 Keigley 1111 3,788,173 [4 Jan. 29,1974

[ 1 HYDRAULIC HAND TOOL Ronald E. Keigley, 219 Laurel Ln., Clarksburg, W. Va.

[22] Filed: Dec. 15,1972

[21] Appl. No.: 315,281

[76] lnventor:

[5 7] ABSTRACT The specification discloses a hydraulic pressure operated hand tool of the type in which manual pressure exerted on a small-area pump piston creates a hydraulic pressure which is communicated to a power cylinder for activating a hand tool jaw member, such as a cutter blade. Preliminary take-up movement of the cutter blade into contact with the object to be severed, such as cables, pipe etc., is effected by manual pressure applied to a second pump piston of relatively large area, which causes rapid displacement of the hydraulic medium from a reservoir to the power cylinder before exertion of manual pressure to the small-area pump piston. A push-button valve when pressed causes instant return displacement of hydraulic medium via a by-pass communication from the cylinder to the reservoir to relieve the activating pressure on the cutter blade and restore it promptly to normal position.

11 Claims, 5 Drawing Figures HYDRAULIC HAND TOOL This invention relates to a hydraulic pressure operated hand tool wherein the exertion of manual pressure on a pump piston communicates an amplified force via a hydraulic medium to a power cylinder for activating a jaw member, such as a cutter blade.

Hand tools, in the form of pliers, presses, or cutters, utilizing a hydraulic medium for force amplification have long been known, as represented typically in U.S. Pat. No. 343,780, issued June 15, I886; US. Pat. No. 2,096,574, issued Oct. I9, 1937; and US. Pat. No. 2,979,032, issued Apr. 11, 1961. In the latter patent, a pair of cutter blades are arranged tong-like for activation by opposing pistons on which hydraulic pressure is built-up by manually effected oscillatory movement of a pump piston. Pressure on the opposing pistons may be relieved via a relief valve in by-pass of the pump piston.

In a more recent patent, US. Pat. No. 3,058,214, issued Oct. 16, 1962, a hydraulically operable hand tool utilizes a pivoted jaw member, such as a cutter blade, in cooperation with a stationery plate or jaw member. A pivoted handle is arranged, in cooperation with the cutter blade, to first mechanically move the cutter blade into contact with the object to be severed, and then exert pressure on a pump piston to transmit hydraulic pressure to a power cylinder for high-pressure activation of the cutter blade. Instant relief of activation pressure may be effected via a manually operated by-pass check valve.

The hand operated tools described in the foregoing patents are of the one-hand type with limited capacity and unsuited, for example to sever large diameter multi-strand copper cable. In order to provide a hydraulic hand tool ofadequate capacity and which avoids other disadvantages of the devices in the foregoing patents, I have provided a hydraulic hand tool in which the force exerted on a pivoted lever, carrying a jaw member in the form of a cutter blade, is automatically increased with increased displacement of the lever toward the severing position of the cutter blade.

More specifically, I have provided a pivoted lever, on which a jaw member in the form of a cutter blade is removably attached, having a cam surface with which the distal end of the piston rod in a power cylinder cooperates so as to provide an increase in the moment arm by which the power cylinder exerts a pivoting force on the lever with increasing displacement of the lever toward its final position.

I further provide a hand tool having a manually operable pump piston of relatively. large area and a manually operable pump piston of relatively small area, the former for effecting rapid large volume displacement of hydraulic medium to the power cylinder actuating the cutter blade lever to cause rapid take-up movement to effect contact with the object to be severed and the latter for developing high hydraulic pressure by which the power cylinder activates the cutter blade.

The above features and other features are hereinafter more specifically described in connection with the accompanying drawings wherein:

FIG. 1 is an elevational view of a preferred embodiment of a hydraulic hand tool embodying my invention;

FIG. 2 is a fragmental plan view of the embodiment of FIG. 1 on enlarged scale;

FIG. 3 is a sectional view, taken on the line III-III of FIG. 2;

FIG. 4 is a fragmental sectional view, taken on the line IVIV of FIG. 2; and

FIG. 5 is a sectional view, taken on the line VV of FIG. 1 showing details of the replaceable cutter blade.

Referring to the drawings, the preferred embodiment of hydraulic hand tool shown, comprises a metal base 11, preferably of the order of 18 inches long, 4 inches wide and 54 inches thick. Affixed to the upper surface of the base 11 in longitudinally spaced relation, are a pressure cylinder casing 12 and a power cylinder 13.

As shown in detail in FIGS. 2 and 3, the pressure cylinder of casing 12 comprises a rectangular base portion 14 having lugs 15 on the corners thereof for attaching the casing 12 to the base by machine screws 16. Formed integrally with or welded to the base portion 14 is a cylinder portion 17 having a bore 18, which serves as a reservoir for hydraulic fluid, in which a piston 19 operates. Piston 19 is a metal disc closely conforming in diameter to that of the bore 18 and having a circumferential groove carrying an O-ring or grommet 20 forming a seal with the wall of the cylinder portion 117. I

Piston 19 has an operating stem 21 secured coaxially thereto which extends upwardly through a central hole 22 in an end cover 23 screwed into the upper end of the cylinder portion 17. .A knob 24 is attached, as by threads, to the upper end of stem 21 for convenient manual operation of the piston 19, as more fully described later on.

In the base portion 14, a longitudinally extending bore 25 is provided into which a small diameter tube 26 constituting a pump cylinder is secured as by a screwthreaded connection. Tube 26 has a longitudinal bore 27 therein in which operates a pump plunger comprising a small-area piston 28 and a coaxial stem 29. Stem 29 extends outwardly through a central hole 30 in an end collar 31, screwed on the outer end of the tube 26. Piston 28 comprises a metal disc closely conforming in diameter to the bore 27 in tube 26 and having a peripheral groove containing aseal in the form of an O-ring or grommet 32. I

The bore 27 in tube 26 communicates via an orifice 33 at the inner end of the tube 27 with the inner end of bore 25. The inner end of bore 25 communicates through a passage 34, containing a check valve 35, with the bottom surface of the bore 18 in the cylinder portion 17. Check valve 35 is illustratively shown as of a ball type and seated by a coil spring 36 in the direction of the bore 18 in the cylinder portion 17. I

The inner end of bore 25 also communicates by way of a passage 37, containing a check valve 38, with a port 39 opening at the right-hand end face of the'base portion 14. The check valve 38 is illustratively shown in FIG. 3 as of a ball type and biased into seated position toward the bore 25 by a spring 40.

There is further provided in the right-hand end face of the base portion 14 a port 42 (Figure 2) which communicates through a passage 43 with the bottom of bore 18 of the cylinder portion 17. Intersecting the passage 43 is a bore 44 containing a spool valve 45. Spool valve 45 is normally biased by a spring 46 outwardly of the bore 44 to a position in which one end of the spool valve blocks communication through the passage 43. Spool valve 45 is shifted inwardly of the bore 44to open communication through the passage 43 by exerting pressure on a push button 46 which is connected by way of a stem or Bowden wire cable 47 to the spool valve.

Attached to the upper face of the base 11 adjacent the outer end of the stem 29 of the plunger is a support arm 48 (FIG. 1) for a handle 49. Handle 49 is pivoted on one side of the arm 48, as by a pin or bolt 50, in alignment with the plunger stem 29. Handle 49 has a curved recess 51 in which the outer end of the plunger stem 29 seats. When pressure is exerted downwardly on a longitudinal portion 52 of the handle, as by the palm of the hand, a corresponding force is exerted inwardly on the plunger stem 29.

The power cylinder 13 is attached, as by welding, to a base portion 55 which has a plurality of lugs 56, one of which is shown in FIG. 1, by which the cylinder is attached to the base 11, using machine screws 57.

For a reason later made apparent, cylinder 13 is supported on base portion 55 at an angle, such as from the vertical. Cylinder 13 has a bore 58 in which operates a piston 59 having a stem 60 which projects slidably through a hole in the end cover 61. End cover 61 is attached as by being screwed into the outer end portion'of the bore 58 in cylinder 13. Piston 59 has a peripheral O-ring or grmmet 62 which seals on the cylinder wall.

Pivotally mounted on a post 63, attached to or formed on the base 11, is a lever 64, the plane of movement of the lever registering with the stem 60 of cylinder 13. Lever 64 has a central clevis portion 65 which straddles the upper end of the post 63 and is pivoted thereon, as by a pin or bolt 66.

A coil tension spring 67, connected at one end to the lever 64 and anchored at the other end to a lug 68 on the base 11, biases the lever pivotally in a counterclockwise direction to effect engagement of cam surface 69, on the lower edge of the lever, with the end of the piston stem 60 of cylinder 13.

A jaw member, such as a cutter blade 70, of generally T-shaped cross section (FIG. 1), is removably attached to the opposite end of the lever 64. As will be seen in FIG. 5, the upper end of the cutter blade is tapered and slides end-wise into a dove-tail slot 71 in the lower edge of the lever 64 and is secured therein by a plurality of set screws 72 engaging tapped bores 73.

With the cam surface on lever 64 engaging the end of the piston stem 60 while in its fully retracted position as shown in FlG. l, the inclination of the cutting edge of the cutter blade 70 is such that on full extension of the piston stem 60, the cutting edge meets the serrated or knurled face of a jaw member, in the form of a plate 74 secured in the base 11, in parallel coinciding relation.

The cam surface 69 on the lever 64 is of such contour that the end of the piston stem 60 remains in contact with the lever 64 as the piston stem 60 moves linearly outward with increasing hydraulic pressure exerted on the piston 59. Moreover, as the angle of the lever 64 changes with outward movement of piston stem 60 the moment arm with which the force of piston stem 60 is exerted becomes progressively greater. Thus the force with which the cutter blade 70 is pressed into the object to be severed is automatically increased accordingly.

Referring now to FIGS. 1 and 2, it will be seen that port 39 in the base portion 14 of the casting 12 is connected by tubing, such as sinch brass tubing 75 and suitable brass fittings 76 to a port 77 in the base 55 of cylinder 13. Port 77 is connected by a passage 78 to the chamber at the pressure side of piston 59 in cylinder bore 18.

In a similar manner, port 42 in the base portion 14 of the pressure casing 12 is connected by tubing, such as Vs inch brass tubing 75' and suitable brass fittings 76 to a port in the base 55 of cylinder 13, which, in turn, is connected by a passage (not shown) to the chamber or the pressure side of the piston 59in cylinder bore 18.

In operation, let it be assumed that the object to be severed such as a multi-strand cable 80, is inserted between the cutter blade and the plate 74 as in the position indicated by broken lines in FIG. 1.

To first effect engagement of the edge of the cutter blade with the cable 80, the operator presses manually on the knob 24 of stem 21, as with the palm of the hand. As the piston'l9 presses downwardly on the hydraulic medium, such as oil, in the pressure chamber within bore 18, oil is displaced rapidly and in substantial volume (due to the relatively larger area of piston 19) through passage 34, past check valve 35, through bore 25, passage 37 and past check valve 38 into tubing and thence through passage 78 to the pressure chamber within bore 58 of cylinder 13. In consequence of the displacement of oil as just described, piston 59 of cylinder 13 shifts outwardly thereby exerting a turning or pivoting movement of lever 64 sufficient to effect engagement of cutter blade 70 with the cable 80.

Once the blade 70 contacts the cable 80, the opera tor may now depress the portion 52 of handle 49 downwardly to exert a force on plunger stem 29. In consequence, the relatively small area piston 28 of the plunger exerts pressure on the oil now in the system to develop the desired amplified'high pressure on piston 59 of cylinder 13.

With the increased hydraulic pressure on piston 59, the piston stem moves progressively outward, With increased outward movement of piston stem 60, the turning moment arm on the lever 64 progressively increases, thereby progressively increasing the force with which cutter blade 70 cuts through the cable. With full travel of piston 59, the cutting edge of blade 70 will have met the plate 74, thereby completing the severance of the cable. V

In order to effect rapid withdrawal of the blade 70 from the cable the operator now presses the push button 46. Such action shifts the spool valve 45 to open a pressure release communication directly from the pressure chamber of cylinder 13 through passage 43 to the oil reservoir or cylinder bore 18. The force of tension spring 67, exerted via the lever 64, on the piston stem 60 restores the piston 59 downwardly to thereby displace the oil rapidly back to the reservoir or cylinder bore 18. As soon as the cutter blade is restored to its normal position, the operator may release the push button 46, in consequence of which the spring 46 restores the spool valve 45 back to its normal position.

While a preferred embodiment of the invention has been shown and described, it will be apparent that variations in structure and use may be made within the terms of the following claims. Thus, for example, it will be apparent that various forms of jaw members may be employed in lieu of the cutter blade 70 and plate 74, for purposes of pressing or gripping.

I claim 1. A hand tool comprising a base having a jaw member fixed thereon; a lever pivoted on said base and having ajaw member fixed thereon; resilient means biasing said lever to a normal position in which said jaw members are separated; pressure responsive means for pivotally moving said lever to effect the cooperative relation of said jaw members; a hydraulic pressure system having a reservoir, a pump having a piston of relatively small area and conduit means communicating hydraulic pressure created by operation of said pump to said pressure responsive means; wherein the improvement comprises a second pump having a piston of relatively large area, operative to rapidly displace a relatively large volume of hydraulic medium from said reservoir to said pressure responsive means to effect the initial movement of said lever whereby closing contact of said jaw members with the object interposed therebetween is effected.

2. A hand tool according to claim 1, wherein the piston of said second pump has a stem having means thereon by which to apply pressure manually to said pump piston.

3. A hand tool according to claim 1, wherein the piston of said second pump is arranged to exert pressure directly on the hydraulic medium in said reservoir.

4. A hand tool according to claim 1, wherein conduit means provides communication between said reservoir and said pressure responsive means, and check valve means in said conduit means serves to prevent back flow of hydraulic medium to said reservoir'upon operation of the first said pump.

5. A hand tool according to claim 1, wherein conduit means provides communication between said reservoir and said pressure responsive means, and a pair of check valves is interposed therein, one of which serves to prevent back flow of hydraulic medium from said pressure responsive means to the. first said pump piston and the second said pump piston, and the other of which serves to prevent back flow to said reservoir on operation of the first said pump piston.

6. A hand tool according to claim 1, wherein a conduit means provides a pressure release communication directly from said pressure responsive means back to said reservoir for rapid return displacement of hydraulic medium thereto, and normally closed valve means in said conduit means is operative to open communication therethrough.

7. A hand tool according to claim 1, wherein conduit means provides communication between said reservoir and said pressure responsive means, check valve means in said conduit means serves to prevent back flow of hydraulic medium from said pressure responsive means to said reservoir, a second conduit means provides pressure release communication directly from said pressure responsive means back to said reservoir in by pass of the first said conduit means for rapid return displacement of hydraulic medium thereto; and normally closed valve means in the said second conduit means is operative to open communication therethrough.

8. A hand tool according to claim 1, wherein said lever has a cam surface thereon, and wherein said pressure responsive means comprises a power cylinder fixed to said base and having a piston the stem of which projects coaxially into contact with said cam surface, linear projection of said piston stem while in contact with said cam surface effecting automatically a progressive increase in the moment arm effective to rock said lever.

9. A hand tool according to claim 1, wherein the jaw member on said base comprises a flat plate member and wherein the jaw member on said lever comprises a cutter blade member fixed on said lever, the cutting edge of said blade member being operative into cooperative seated engagement with the said flat plate member to effect full severance of an object interposed therebetween.

10. A hand tool according to claim 9, wherein the said blade member is of generally T-shaped crosssection, the said lever has a dovetail slot, and the upper portion of the said blade member is tapered to interlock in said dovetail slot in said lever.

11. A hand tool according to claim 10, wherein said lever is provided with tapped bores intersecting the dovetail slot therein, and screws are provided in said tapped bores to engage said blade member to press it into frictionally locked engagement in said dovetail slot. 

1. A hand tool comprising a base having a jaw member fixed thereon; a lever pivoted on said base and having a jaw member fixed thereon; resilient means biasing said lever to a normal position in which said jaw members are separated; pressure responsive means for pivotally moving said lever to effect the cooperative relation of said jaw members; a hydraulic pressure system having a reservoir, a pump having a piston of relatively small area and conduit means communicating hydraulic pressure created by operation of said pump to said pressure responsive means; wherein the improvement comprises a second pump having a piston of relatively large area, operative to rapidly displace a relatively large volume of hydraulic medium from said reservoir to said pressure responsive means to effect the initial movement of said lever whereby closing contact of said jaw members with the object interposed therebetween is effected.
 2. A hand tool according to claim 1, wherein the piston of said second pump has a stem having means thereon by which to apply pressure manually To said pump piston.
 3. A hand tool according to claim 1, wherein the piston of said second pump is arranged to exert pressure directly on the hydraulic medium in said reservoir.
 4. A hand tool according to claim 1, wherein conduit means provides communication between said reservoir and said pressure responsive means, and check valve means in said conduit means serves to prevent back flow of hydraulic medium to said reservoir upon operation of the first said pump.
 5. A hand tool according to claim 1, wherein conduit means provides communication between said reservoir and said pressure responsive means, and a pair of check valves is interposed therein, one of which serves to prevent back flow of hydraulic medium from said pressure responsive means to the first said pump piston and the second said pump piston, and the other of which serves to prevent back flow to said reservoir on operation of the first said pump piston.
 6. A hand tool according to claim 1, wherein a conduit means provides a pressure release communication directly from said pressure responsive means back to said reservoir for rapid return displacement of hydraulic medium thereto, and normally closed valve means in said conduit means is operative to open communication therethrough.
 7. A hand tool according to claim 1, wherein conduit means provides communication between said reservoir and said pressure responsive means, check valve means in said conduit means serves to prevent back flow of hydraulic medium from said pressure responsive means to said reservoir, a second conduit means provides pressure release communication directly from said pressure responsive means back to said reservoir in by-pass of the first said conduit means for rapid return displacement of hydraulic medium thereto; and normally closed valve means in the said second conduit means is operative to open communication therethrough.
 8. A hand tool according to claim 1, wherein said lever has a cam surface thereon, and wherein said pressure responsive means comprises a power cylinder fixed to said base and having a piston the stem of which projects coaxially into contact with said cam surface, linear projection of said piston stem while in contact with said cam surface effecting automatically a progressive increase in the moment arm effective to rock said lever.
 9. A hand tool according to claim 1, wherein the jaw member on said base comprises a flat plate member and wherein the jaw member on said lever comprises a cutter blade member fixed on said lever, the cutting edge of said blade member being operative into cooperative seated engagement with the said flat plate member to effect full severance of an object interposed therebetween.
 10. A hand tool according to claim 9, wherein the said blade member is of generally T-shaped cross-section, the said lever has a dovetail slot, and the upper portion of the said blade member is tapered to interlock in said dovetail slot in said lever.
 11. A hand tool according to claim 10, wherein said lever is provided with tapped bores intersecting the dovetail slot therein, and screws are provided in said tapped bores to engage said blade member to press it into frictionally locked engagement in said dovetail slot. 